The Reverse Blocking GTO as a Very Fast Turn-Off Thyristor

High-frequency operation of GTOs in parallel inverter with resonant load for induction heating is investigated. Load-forced turn-off process of devices having reverse blocking capability is studied and analyzed on the basis of experimental results. The behaviour of the anode and gate voltages and currents during turn-off and during reapplication of the forward voltage is analyzed in dependence of various operating parameters (rate of decrease of anode current, rate of rise of anode voltage, reverse bias amplitude and duration) and in particular on the timing of gate command. Appreciable benefits in terms of commutation losses, turn-off time and snubber reduction are obtained, as compared with the usual performance in chopper operation. Indications for an optimal gate control strategy are also given.